Structure and diffusive properties of fluid-filled grain boundaries: An in-situ study using infrared (micro) spectroscopy
Structure and diffusive properties of fluid-filled grain boundaries: An in-situ study using infrared (micro) spectroscopy
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DOI：
10.1016/j.epsl.2004.12.030
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发表时间：
2005-04-15
影响因子：
5.3
通讯作者：
Nakashima, S
中科院分区：
文献类型：
--
作者：
de Meer, S;Spiers, CJ;Nakashima, S
地壳岩石系统中许多成岩、变形和变质过程的速率最终取决于含水颗粒边界的结构和扩散性质。我们提出了第一个原位光谱研究的性质的水膜存在于矿物界面进行应力诱导溶解或“压力溶液”。利用红外显微光谱，我们表明，在积极的压力溶解的（111）面的岩盐（NaCl）对CaF 2板，受限的晶间液体的平均厚度为85-185 nm，并占据一个粗糙的，非平衡的晶界结构。由于向冰状（硬）水的聚合增加，晶界膜内的水的氢键被改性。同时的压力解决方案，我率测量表明，在晶界流体的扩散是约一个数量级慢于体相溶液。在岩盐（100）面的主动压力溶解过程中，也出现了类似的非平衡增益边界结构，但水膜的平均厚度只有40 nm左右，没有发现水的氢键发生改变的证据。研究的两种取向之间的氢键的差异归因于NaCl中的（111）和中性（100）界面上的表面电荷分布的差异。平均膜厚度的差异归因于溶解NaCl表面的晶体学控制的粗糙度的差异。如果类似的晶界厚度和扩散效应发生在其他岩石形成矿物，在这种系统中的压力溶液将倾向于界面反应控制，并可能能够产生显着的地震各向异性。(c)2005 Elsevier B. V.保留所有权利。
The rate of numerous diagenetic, deformation and metamorphic processes in crustal rock systems ultimately depends on the structure and diffusive properties of water-bearing grain boundaries. We present the first in-situ spectroscopic study of the nature of aqueous films present in mineral interfaces undergoing stress-induced dissolution or 'pressure solution'. Using infrared micro-spectroscopy, we show that during active pressure dissolution of the (111) plane of halite (NaCl) against a CaF2 plate, the confined intercrystalline liquid has an average thickness of 85-185 mn and occupies a rough, non-equilibrium grain boundary structure. The hydrogen bonding of the water within the grain boundary film is modified due to increased polymerization towards ice-like (hard) water. Simultaneous pressure solution I rate measurements show that diffusion within the grain boundary fluid is about one order of magnitude slower than in bulk solution. During active pressure solution of the (100) plane of halite, a similar non-equilibrium gain boundary structure develops but the average thickness of the confined water film is only similar to 40 nm and no evidence is found for modification of the hydrogen bonding of the Water. The difference in hydrogen bonding between the two orientations studied is attributed to differences in surface charge distribution on the (111) and neutral (100) interfaces in NaCl. The difference in mean film thickness is attributed to differences in crystallographically controlled roughness of the dissolving NaCl Surface. If similar grain boundary thickness and diffusivity effects occur in other rock forming minerals, pressure solution in such systems will tend to be interface reaction controlled and may be capable of producing significant seismic anisotropy. (c) 2005 Elsevier B.V. All rights reserved.